1. Field of the Invention
The present invention relates to a thin film transistor structure and the manufacturing method thereof, and more particularly to a thin film transistor source/drain structure and the manufacturing method thereof.
2. Description of the Related Art
The demand for smaller electronic consumer products with higher resolution displays, spurs continued research and development in the area of liquid crystal displays (LCDs). The size of LCDs can be controlled by incorporating the large-scale integration (LSI) and very large scale integration (VLSI) driver circuits, presently on the periphery of LCDs, into the LCD itself. The elimination of externally located driving circuits and transistors will reduce product size, process complexity, a number of process steps, and ultimately the price of the product in which the LCD is mounted.
The primary component of the LCD, and the component that must be enhanced for further LCD improvements to occur, is the thin-film transistor (TFT). TFTs are typically fabricated on a transparent substrate such as quartz, glass, or even plastic. TFTs are almost exclusively used as switches to allow the various pixels of the LCD to be charged in response to the driver circuits. TFT performance will be improved, and driver circuit functions incorporated into TFTs, by increasing the electron mobility in the TFT devices. Increasing the electron mobility of a transistor results in a transistor having faster switching speeds. Improved TFTs having increased electron mobility yield controllable LCD screens, lower power consumption, and faster transistor response times. Further LCD resolution enhancements will require that the TFTs mounted on the transparent substrates have electron mobility characteristics rivaling IC driver circuits currently mounted along the edges of the screen. That is, display and driver TFT located across the entire display must operate at substantially the same level of performance.
RC(Resistance and Capacitance)time delay of TFTs of large-size and high resolution LCD is crucial factor since large RC delay would drags switching speed of TFTs. That is, the resistance or capacitance of TFTs must be further decreased. Due to the characteristic properties of TFTs processes, the materials and processes of source and drain of TFTs are much more critical than those of conventional transistors of integrated circuits. Moreover, the materials of source and drain of conventional TFTs can not satisfy the requirements of large-size and high resolution LCD. For example, the conventional material of source and drain of TFTs is chrome which has resistivity about 18 μΩ and such high resistivity will not meet the requirements of modern large-size and high resolution LCDs.
In view of the drawbacks mentioned with the prior art source and drain structure and process thereof, there is a continued need to develop new and improved structures and processes that overcome the disadvantages associated with prior art structures and processes. The advantages of this invention are that it solves the problems mentioned above.